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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Networking Working Group Ran. Chen 3 Internet-Draft Zheng. Zhang 4 Intended status: Standards Track ZTE Corporation 5 Expires: May 28, 2021 Senthil. Dhanaraj 6 Huawei 7 Fengwei. Qin 8 China Mobile 9 November 24, 2020 11 PCEP Extensions for BIER-TE 12 draft-chen-pce-bier-08 14 Abstract 16 Bit Index Explicit Replication (BIER)-TE shares architecture and 17 packet formats with BIER as described in [RFC8279]. BIER-TE forwards 18 and replicates packets based on a BitString in the packet header, but 19 every BitPosition of the BitString of a BIER-TE packet indicates one 20 or more adjacencies as described in [I-D.ietf-bier-te-arch].BIER-TE 21 Path can be derived from a Path Computation Element (PCE). 23 This document specifies extensions to the Path Computation Element 24 Protocol (PCEP) that allow a PCE to compute and initiate the path for 25 the BIER-TE. 27 Status of This Memo 29 This Internet-Draft is submitted in full conformance with the 30 provisions of BCP 78 and BCP 79. 32 Internet-Drafts are working documents of the Internet Engineering 33 Task Force (IETF). Note that other groups may also distribute 34 working documents as Internet-Drafts. The list of current Internet- 35 Drafts is at https://datatracker.ietf.org/drafts/current/. 37 Internet-Drafts are draft documents valid for a maximum of six months 38 and may be updated, replaced, or obsoleted by other documents at any 39 time. It is inappropriate to use Internet-Drafts as reference 40 material or to cite them other than as "work in progress." 42 This Internet-Draft will expire on May 28, 2021. 44 Copyright Notice 46 Copyright (c) 2020 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (https://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 62 2. Conventions used in this document . . . . . . . . . . . . . . 3 63 3. Overview of PCEP Operation in BIER Networks . . . . . . . . . 3 64 4. Object Formats . . . . . . . . . . . . . . . . . . . . . . . 3 65 4.1. The OPEN Object . . . . . . . . . . . . . . . . . . . . . 3 66 4.1.1. The BIER-TE PCE Capability sub-TLV . . . . . . . . . 3 67 4.2. The RP/SRP Object . . . . . . . . . . . . . . . . . . . . 4 68 4.3. END-POINTS object . . . . . . . . . . . . . . . . . . . . 4 69 4.4. ERO Object . . . . . . . . . . . . . . . . . . . . . . . 4 70 4.4.1. BIER-ERO Subobject . . . . . . . . . . . . . . . . . 5 71 4.4.2. BIER-ERO Processing . . . . . . . . . . . . . . . . . 6 72 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 73 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 74 6.1. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . 6 75 6.1.1. BIER-TE-PCE-CAPABILITY Sub-TLV Type Indicators . . . 6 76 6.1.2. New Path Setup Type . . . . . . . . . . . . . . . . . 7 77 6.1.3. BIER-ERO Subobject . . . . . . . . . . . . . . . . . 7 78 6.1.4. PCEP-Error Objects and Types . . . . . . . . . . . . 7 79 7. Normative references . . . . . . . . . . . . . . . . . . . . 8 80 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 82 1. Introduction 84 Bit Index Explicit Replication (BIER)-TE shares architecture and 85 packet formats with BIER as described in [RFC8279]. BIER-TE forwards 86 and replicates packets based on a BitString in the packet header, but 87 every BitPosition of the BitString of a BIER-TE packet indicates one 88 or more adjacencies as described in [I-D.ietf-bier-te-arch].BIER-TE 89 Path can be derived from a Path Computation Element (PCE). 91 [RFC8231] specifies a set of extensions to PCEP that allow a PCE to 92 compute and recommend network paths in compliance with [RFC4657] and 93 defines objects and TLVs for MPLS-TE LSPs. 95 This document uses a PCE for computing one or more BIER-TE paths 96 taking into account various constraints and objective functions. 98 2. Conventions used in this document 100 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 101 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 102 document are to be interpreted as described in RFC2119. 104 3. Overview of PCEP Operation in BIER Networks 106 BIER-TE forwards and replicates packets based on a BitString in the 107 packet header, and every BitPosition of the BitString of a BIER-TE 108 packet indicates one or more adjacencies as described in 109 [I-D.ietf-bier-te-arch]. In a PCEP session, An ERO object specified 110 in [RFC5440] can be extended to carry a BIER-TE path consists of one 111 or more BIER-ERO subobject(s). BIER-TE computed by a PCE can be 112 represented in the following forms: 114 o An ordered set of adjacencies BitString(s) in which each bit 115 represents that the adjacencies to which the BFR should replicate 116 packets to in the domain. 118 In this document, we define a set of PCEP protocol extensions, 119 including a new PCEP capability,a new Path Setup Type (PST) ,a new 120 BIER END-POINT Object, new ERO subobjects, new PCEP error codes and 121 procedures. 123 4. Object Formats 125 4.1. The OPEN Object 127 4.1.1. The BIER-TE PCE Capability sub-TLV 129 [RFC8408]defines the PATH-SETUP-TYPE-CAPABILITY TLV for use in the 130 OPEN object. The PATH-SETUP-TYPE-CAPABILITY TLV contains an optional 131 list of sub-TLVs which are intended to convey parameters that are 132 associated with the path setup types supported by a PCEP speaker. 134 This document defines a new Path Setup Type (PST) for BIER as 135 follows: 137 o PST = TBD2: Path is setup using BIER-TE technique. 139 A PCEP speaker MUST indicate its support of the function described in 140 this document by sending a PATH-SETUP-TYPE-CAPABILITY TLV in the OPEN 141 object with this new PST included in the PST list. 143 This document also defines the BIER-TE-PCE-CAPABILITY sub-TLV. PCEP 144 speakers use this sub-TLV to exchange BIER capability. If a PCEP 145 speaker includes PST=TBD1 in the PST List of the PATH-SETUP-TYPE- 146 CAPABILITY TLV then it MUST also include the BIER-TE-PCE- CAPABILITY 147 sub-TLV inside the PATH-SETUP-TYPE-CAPABILITY TLV. 149 The format of the BIER-TE-PCE-CAPABILITY sub-TLV is shown in the 150 following figure: 152 0 1 2 3 153 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 154 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 155 | Type=TBD1 | Length | 156 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 157 | Reserved | Flags | 158 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 160 Figure 1 BIER-TE-PCE-CAPABILITY sub-TLV format 162 The code point for the TLV type is to be defined by IANA. 164 Length: 4 bytes. 166 The "Reserved" (2 octet) and "Flags" (2 octet) fields are currently 167 unused, and MUST be set to zero on transmission and ignored on 168 reception. 170 4.2. The RP/SRP Object 172 In order to setup an BIER-TE, a new PATH-SETUP-TYPE TLV MUST be 173 contained in RP/SRP object. This document defines a new Path Setup 174 Type (PST=TBD2) for BIER-TE. 176 4.3. END-POINTS object 178 The END-POINTS object which is defined in [RFC8306]is used in a PCReq 179 message to specify the BIER information of the path for which a path 180 computation is requested. To represent the end points for a BIER 181 path efficiently, we reuse the P2MP END-POINTS object body for 182 IPv4(Object-Type 3) and END-POINTS object body for IPv6 (Object-Type 183 4) which is defined in [RFC8306]. 185 4.4. ERO Object 187 BIER-TE consists of one or more adjacencies BitStrings where every 188 BitPosition of the BitString indicates one or more adjacencies, as 189 described in([RFC8279]). 191 The ERO object specified in [RFC5440] is used to encode the path of a 192 TE LSP through the network.The ERO is carried within a PCRep message 193 to provide the computed TE LSP if the path computation was 194 successful.In order to carry BIER-TE explicit paths, this document 195 defines a new ERO subobjects referred to as "BIER-ERO subobjects" 196 whose formats are specified in the following section. An BIER-ERO 197 subobjects carrying a adjacencies BitStrings consists of one or more 198 BIER-ERO subobject(s). 200 4.4.1. BIER-ERO Subobject 202 0 1 2 3 203 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 204 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 205 |L| Type=TBD3 | Length | 206 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 207 | BS Length | subdomain-id | SI | Reserved | 208 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 209 | Adjacency BitString (first 32 bits) ~ 210 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 211 ~ ~ 212 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 213 ~ Adjacency BitString (last 32 bits) | 214 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 216 Figure 3 218 The 'L' Flag: Indicates whether the subobject represents a loose-hop 219 in the LSP[RFC3209]. If the bit is not set, the subobject represents 220 a strict hop in the explicit route. 222 Type: TBD3 224 Length: 1 octet ([RFC3209]). Contains the total length of the 225 subobject in octets. The Length MUST be at least 8, and MUST be a 226 multiple of 4. 228 BS Length: A 1 octet field encodes the length in bits of the 229 BitString as per [RFC8296], the maximum length of the BitString is 5, 230 it indicates the length of BitString is 1024.It is used to refer to 231 the number of bits in the BitString. 233 subdomain-id: Unique value identifying the BIER subdomain. 1 octet. 235 SI: Set Identifier (Section 1 of [RFC8279] used in the encapsulation 236 for this BIER subdomain for this BitString length, 1 octet. 238 The "Reserved" (1 octets) fields are currently unused, and MUST be 239 set to zero on transmission and ignored on reception. 241 Adjacency BitString: a variable length field encoding the Adjacency 242 BitString where every BitPosition of the BitString indicates one or 243 more adjacencies.the length of this field is according the BS length. 244 The minimum value of this field is 64 bits, and the maximum value of 245 this field is 1024 bits. 247 Notice: 249 The maximum value of BS Length is limited to the 1024 bits, in case 250 the BIER-ERO Subobject is too long. 252 4.4.2. BIER-ERO Processing 254 The ERO and SR-ERO subobject processing remains as per [RFC5440]. 256 If a PCC receives an BIER-ERO subobject in which either 257 BitStringLength or Adjacency BitString or SI is absent, it MUST 258 consider the entire BIER-ERO subobject invalid and send a PCErr 259 message with Error-Type = 10 ("Reception of an invalid object"), 260 Error-Value = TBD5 ("BitStringLength is absent ") or Error-Value = 261 TBD6 ("Adjacency BitString is absent")or Error-Value = TBD7("SI is 262 absent "). 264 If a PCC receives an BIER-ERO subobject in which BitStringLength 265 values are not chosen from: 64, 128, 256, 512, 1024, as it described 266 in ( [RFC8279]). The PCC MUST send a PCErr message with Error-Type 267 =10 ("Reception of an invalid object") and Error-Value = TBD8 268 ("Invalid BitStringLength"). 270 5. Security Considerations 272 TBD. 274 6. IANA Considerations 276 6.1. PCEP Objects 278 IANA has made the following Object-Type allocations from the "PCEP 279 Objects" sub-registry. 281 6.1.1. BIER-TE-PCE-CAPABILITY Sub-TLV Type Indicators 282 vlaue Meaning Reference 283 -------------- ----------------------- ------------- 284 TBD1 BIER-TE-PCE-CAPABILITY This Document 286 6.1.2. New Path Setup Type 288 vlaue Meaning Reference 289 -------------- ----------------------- ------------- 290 TBD2 Path is setup using BIER 291 TE technique This Document 293 6.1.3. BIER-ERO Subobject 295 This document defines a new subobject type for the BIER explicit 296 route object (ERO),The code points for subobject types of these 297 objects is maintained in the RSVP parameters registry. 299 Object Sub-Object Sub-Object Type 300 ----------------- ----------------------- ----------------- 301 EXPLICIT_ROUTE BIER-ERO (PCEP-specific) TBD3 303 6.1.4. PCEP-Error Objects and Types 305 IANA is requested to allocate code-points in the "PCEP-ERROR Object 306 Error Types and Values" subregistry for the following new error-types 307 and error-values: 309 Error-Type Meaning Reference 310 --------- --------------------------- ---------------- 311 10 Reception of an invalid object RFC5440 313 Error-value = TBD4 This document 314 BitStringLength is absent 316 Error-value = TBD5 This document 317 Adjacency BitString is absent 319 Error-value = TBD6 This document 320 SI is absent 322 Error-value = TBD7 This document 323 Invalid BitStringLength 325 7. Normative references 327 [I-D.ietf-bier-te-arch] 328 Eckert, T., Cauchie, G., and M. Menth, "Tree Engineering 329 for Bit Index Explicit Replication (BIER-TE)", draft-ietf- 330 bier-te-arch-09 (work in progress), October 2020. 332 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 333 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 334 Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, 335 . 337 [RFC4657] Ash, J., Ed. and J. Le Roux, Ed., "Path Computation 338 Element (PCE) Communication Protocol Generic 339 Requirements", RFC 4657, DOI 10.17487/RFC4657, September 340 2006, . 342 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 343 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 344 DOI 10.17487/RFC5440, March 2009, 345 . 347 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 348 Computation Element Communication Protocol (PCEP) 349 Extensions for Stateful PCE", RFC 8231, 350 DOI 10.17487/RFC8231, September 2017, 351 . 353 [RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 354 Przygienda, T., and S. Aldrin, "Multicast Using Bit Index 355 Explicit Replication (BIER)", RFC 8279, 356 DOI 10.17487/RFC8279, November 2017, 357 . 359 [RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 360 Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation 361 for Bit Index Explicit Replication (BIER) in MPLS and Non- 362 MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January 363 2018, . 365 [RFC8306] Zhao, Q., Dhody, D., Ed., Palleti, R., and D. King, 366 "Extensions to the Path Computation Element Communication 367 Protocol (PCEP) for Point-to-Multipoint Traffic 368 Engineering Label Switched Paths", RFC 8306, 369 DOI 10.17487/RFC8306, November 2017, 370 . 372 [RFC8408] Sivabalan, S., Tantsura, J., Minei, I., Varga, R., and J. 373 Hardwick, "Conveying Path Setup Type in PCE Communication 374 Protocol (PCEP) Messages", RFC 8408, DOI 10.17487/RFC8408, 375 July 2018, . 377 Authors' Addresses 379 Ran Chen 380 ZTE Corporation 382 Email: chen.ran@zte.com.cn 384 Zheng Zhang 385 ZTE Corporation 387 Email: zhang.zheng@zte.com.cn 389 Senthil Dhanaraj 390 Huawei 392 Email: senthil.dhanaraj.ietf@gmail.com 394 Fengwei Qin 395 China Mobile 397 Email: qinfengwei@chinamobile.com